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My invention relates to a novel, revolutionary apparatus and method for the generation of electrical and mechanical power. More particularly, my invention relates to a power plant driven by thrust modules, which are preferably ramjet engines, and to novel rotors designed to withstand the extremely high tensile stress encountered while rotatably securing such thrust modules. The rotors are designed for operation at supersonic tip speeds while maintaining low aerodynamic drag, and are constructed of composite carbon fiber and/or metal matrix composites. Power plants of that character are particularly useful for generation of electrical and mechanical power at substantially improved efficiency rates when compared to various conventional power plant types.
A continuing demand exists for a simple, high efficiency, inexpensive power plant which can reliably provide electrical and mechanical power. A variety of medium size electrical or mechanical power plants could substantially benefit from a prime mover which provides a marked improvement in overall efficiency. Such medium size mechanical or electrical power plantsxe2x80x94in the 10 to 100 megawatt rangexe2x80x94are required in a wide range of industrial applications, including rail locomotives, marine power systems, aircraft engines, and stationary electric power generating units. Power plants in this general size range are also well suited to use in industrial cogeneration facilities. Such facilities are increasingly employed to service industrial thermal power needs while simultaneously generating electrical power.
Power plant designs which are now commonly found in co-generation applications include (a) gas turbines, driven by the combustion of natural gas, fuel oil, or other fuels, and capturing the thermal and kinetic energy from the combustion gases, (b) steam turbines, driven by the steam which is generated in boilers from the combustion of coal, fuel oil, natural gas, solid waste, or other fuels, and (c) large scale reciprocating engines, usually diesel cycle and typically fired with fuel oils.
Each of the aforementioned types of power plants are complex integrated systems. Such plants often include many subsystems and a large number of individual parts. The parts often must be manufactured to exacting dimensional and mechanical specifications. As a result, such power plants are relatively expensive to manufacture, to install, and to operate. Also, in the event of failure of a part or subsystem, the required repairs are often quite expensive. Frequently, repairs may require substantial disassembly of subsystems to gain access to individual parts, in order to repair or replace the faulty components and return the plant to an operational condition.
Of the currently available power plant technologies, diesel fueled reciprocating and advanced turbine engines have the highest efficiency levels. Base efficiencies are often in the range of 25% to 40%, based on net work produced when compared to the energy value of the fuel source. Unfortunately, at power output levels greater than approximately 1 megawatt, the size of the pistons and other engine components required by reciprocating engine systems become almost unmanageably large, and as a result, widespread commercial use of larger sized reciprocating engine systems has not been accomplished.
Gas turbines perform more reliably than reciprocating engines, and are therefore frequently employed in plants which have higher power output levels. However, because gas turbines are only moderately efficient in converting fuel to electrical energy, gas turbine powered plants are most effectively employed in co-generation systems where, as mentioned above, both electrical and thermal energy can be utilized. In that way; the moderate efficiency of a gas turbine can in part be counterbalanced by increasing the overall cycle efficiency.
Fossil fueled steam turbine electrical power generation systems are also of fairly low efficiency, often in the range of 30% to 40%. Such systems are commonly employed in both utility and industrial applications for base load electrical power generation. This is primarily due to the high reliability of such systems. However, like gas turbine equipment, steam turbine equipment is most advantageously employed in situations where both mechanical and thermal energy may be utilized, thus increasing overall cycle efficiency.
Because of their moderate efficiency in conversion of fuel input to electrical output, the most widely used types of power plants, namely gas turbines and combustion powered steam turbine systems, depend upon co-generation in industrial settings to achieve advantageous commercial electricity cost levels. Thus, it can be appreciated that it would be desirable to be able to generate electrical power at higher overall efficiency rates than is commonly achieved today, especially when compared to the currently utilized gas and steam turbine based power plants.
Ramjets are widely know and have been utilized, primarily in aerospace applications, since the 1940s. Basically, a ramjet is a fixed geometry combustion chamber which is propelled through an airstream by the thrust reaction of the chamber against escaping combustion gases which have been generated by oxidizing an injected fuel with the incoming air supply. The configuration of ramjet engine inlets, fuel injection requirements, combustion chamber configurations, and ignition requirements have been the subject of much study and technical development over many years.
Early ramjets were described, for example, in German Patent No. 554, 906, issued Nov. 2, 1932 to Ing. Albert Fono. Ramjets have also been experimentally employed to assist in the rotation of helicopter blades about a central shaft. For example, see the National Advisory Committee for Aeronautics (NACA) research memorandum (NACA RM L53DOZ) for a ramjet powered helicopter rotor. However, insofar as I am aware, ramjets have not been employed in commercial power plants for production of electricity.
I have now invented, and disclose herein, a novel, revolutionary power generation plant design. My power plant design is based on the use of a ramjet engine as the prime mover, and has greatly increased efficiencies when compared to those heretofore used power plants of which I am aware. Unlike most power plants commonly in use today, my power plant design is simple, compact, relatively inexpensive, easy to install and to service, and otherwise superior to currently operating plants of which I am aware.
My novel power plants have a unique low aerodynamic drag rotor portion. The rotor is constructed of metal matrix composites and/or high strength carbon fiber, and can be operated at rotating speeds well above those which would induce tensile and compressive strains that would cause conventional materials such as steel or titanium to fail.
Thus, the rotor design used in my power plant overcomes two important and serious problems: First, at the supersonic tip speeds at which my device operates, the rotor design minimizes aerodynamic drag, thus it minimizes parasitic losses to the power plant due to the drag resulting from the movement of the rotor in an airstream. Second, the composite design provides the necessary tensile and compressive strength, where needed in the rotor, to prevent internal separation of the rotor by virtue of the centrifugal and centripetal forces acting on the rotor materials.
Solving the two aforementioned problems are critical elements of my invention. Operation of a rotary ramjet driven rotating power generation apparatus at the supersonic tip speeds considered desirable for efficient operation would be impossible with conventional construction materials such as high strength steel. Also, it is important that a power plant avoid large parasitic losses that undesirably consume fuel and reduce overall efficiency.
I have now developed novel rotor designs for use in combination with a ramjet driven power generation system, so as to enable high speed, aerodynamically efficient rotor operation. In one embodiment, a biplane rotor includes an upper triangularly shaped portion and an opposing lower triangularly shaped portion; the upper and lower portions both are secured to and extend from opposing sides of a central hub portion. The central hub portion is rotatably secured in an operating position along an axis formed by upper and lower shaft portions. The upper and lower rotor portions are situated so that air may pass above the upper portion and below the lower portion. More importantly, air may pass through a gap between the upper and lower portions with minimal aerodynamic drag.
Attached to the distal end of each pair of rotors are ramjet engine thrust modules. The inward edge portion of the ramjet engine attaches to the outer edge portions of the opposing upper and lower rotor portions, thus affixing the ramjet engine to the rotor. In various embodiments, the ramjet may be further secured to the rotor by either an external endcap or by externally wound composite fiber bundles.
The ramjet engines are situated so as to engage and to compress that portion of the airstream which is impinged by the ramjet upon its rotation about the aforementioned shaft. I have also provided in my design a feature to insure that a relatively clean airstream (free of the rotor""s own wake turbulence) will be encountered by the rotating rotor and ramjet. This is accomplished by circulating, generally along the aforementioned axis of rotation, an airstream which can both replace the gases scooped up by the ramjet compression as well as sweep away the wake from the just turned rotor.
Fuel is added to the air which has been compressed in the ramjet inlet. The fuel may be conveniently provided to the ramjet engine combustion chamber through use of fuel supply passageways communicating between the ramjet and a fuel source. Fuel passageways may allow fuel flow upwardly from the bottom shaft portion and downwardly from the top shaft portion, then such passageways are turned outwardly through the hub portion and thence radially outwardly through either or both of the rotor portions, then on through the outer edge portions, and thence through fuel injection ports to the ramjet engine combustion chambers. The combustion gases formed by oxidation of the fuel escape rearwardly from the ramjet, thrusting the ramjet tangentially about the axis formed by the shaft portions, thus turning the rotor and the shaft portions. The power so generated by the turning shaft may be used directly in mechanical form, or may be used to power an electrical generator and thus generate electricity.
In one embodiment, the outlet portions of the ramjet are positioned so that the combustion gases may impinge on a set of heat transfer elements, so as to cool the combustion gases by way of heating up a heat transfer fluid such as water which is circulated within the heat transfer elements. Ultimately, the cooled combustion gases may be exhausted to the ambient air.
In another important embodiment, an annular reaction turbine is additionally provided surrounding the exit to the exhaust gas heat exchanger. This annular reaction turbine captures the substantial kinetic energy remaining in the exhaust gas flow, so as to improve overall cycle efficiency.
In yet other embodiments, the rotor may be provided in the shape of a disk, discus, or similar shape.
In yet another embodiment, a small central disk rotor with outwardly extending upper and lower biplane rotor portions are provided.
Other embodiments provide further variations in the air flow configuration and in provision of the fuel supply means.
In addition to the foregoing, my novel devices are simple, durable, and relatively inexpensive to manufacture.
From the foregoing, it will be apparent to the reader that one important and primary object of the present invention resides in the provision of novel, improved mechanical devices to generate mechanical and electrical power.
More specifically, an important object of my invention is to provide a ramjet driven power generation plant which is capable of withstanding the stress and strain of high speed rotation, so as to reliably provide a method of power generation at a very high efficiency rate.
Other important but more specific objects of the invention reside in the provision of power generation plants as described in the preceding paragraph which:
allow the generation of power to be done in a simple, direct manner;
have a minimum of mechanical parts;
avoid complex subsystems;
require less physical space than existing technology power plants;
are easy to construct, to start, and to service;
have high efficiency rates; that is, to provide high heat and high work outputs based on heating value of fuel input to the power plant;
in conjunction with the preceding object, provide lower power costs to the power plant operator and thus to the power purchaser than is presently the case;
cleanly burns fossil fuels;
in conjunction with the just mentioned object, results in fewer negative environmental impacts than most power generation facilities currently in use;
have a fuel supply design which efficiently supplies a ramjet;
have a rotating element with a structure able to withstand the stresses and strains of rotating at very high tip speeds; and which
have a rotating element design which provides operation with minimal aerodynamic drag.
A feature of one embodiment of the present invention is the use of a novel biplane rotor which provides minimal aerodynamic drag at the high rotational design speeds, thereby enabling the power plant to minimize parasitic losses, with the resulting advantage of high overall cycle efficiencies.
Another feature of the present invention is the use of a monofilament carbon fiber winding as an integral part of the structure of the rotor, which provides the advantage of high strength, thus enabling operation at rotational speeds above stress failure limits of conventional materials such as steel and titanium.
Other important objects, features, and additional advantages of my invention will become apparent to those skilled in the art from the foregoing and from the detailed description which follows and the appended claims, in conjunction with the accompanying drawing.